A contemporary viewpoint on 'aspirin resistance'

High on-treatment platelet reactivity is associated with poor outcomes after ischemic stroke: A meta-analysis

OBJECTIVES

High on-treatment platelet reactivity (HTPR) determined by platelet function assays is present in certain patients with ischemic stroke or transient ischemic attack (TIA). However, it is unclear whether HTPR is associated with poor clinical outcomes. Our study aimed to investigate the relationship of HTPR with recurrent vascular events in ischemic stroke or TIA.

METHODS

Pubmed (MEDLINE), EMBASE, and Cochrane Library were searched for eligible studies from inception to January 1, 2022. Stata 17.0 software was used to calculate the risk ratio (RR). Subgroup and sensitivity analyses were conducted to assess the source of heterogeneity. A random-effects model was used when heterogeneity was present. Primary endpoint of the meta-analysis was the risk ratio of recurrent vascular events in HTPR Patients. While stroke and TIA, all-cause death, early neurological deterioration, early new ischemic lesions, and stroke severity measured by National Institute of Health Stroke Scale (NIHSS) scores at admission were also pooled.

RESULTS

Thirty articles (7995 patients) were eligible including 28 cohort studies and 2 prospective case-control studies. The prevalence of HTPR varied from 5.9% to 60%. HTPR was associated with an increased risk of recurrent vascular events (RR = 2.94, 95% CI 2.04-4.23), stroke recurrence (RR = 2.05; 95% CI 1.43-2.95), and all-cause mortality (RR = 2.43; 95% CI 1.83-3.22). Subgroup analysis showed that HTPR determined by optical aggregometry, Verify-Now system and 11dh TXB2 is related to a higher risk of recurrent vascular events (RR = 3.53, 95% CI 1.51-9.40; RR = 2.16, 95% CI 1.02-4.56; RR = 3.76, 95% CI 1.51-9.40, respectively). Moreover, patients with HTPR had an increased incidence of early neurological deterioration (RR = 2.75; 95% CI 1.76-4.30) and higher NIHSS scores at admission (Mean difference 0.19, 95% CI 0.01-0.36).

CONCLUSIONS

This meta-analysis demonstrates HTPR is associated with higher risk of recurrent vascular events, early neurological deterioration and increased severity in patients with ischemic stroke and TIA. HTPR measured by platelet function assays may guide the use of antiplatelet agents in ischemic stroke and TIA.

Comparison of Different Laboratory Tests to Identify “Aspirin Resistance” and Risk of Vascular Events among Ischaemic Stroke Patients: A Double-Blind Study

“Aspirin resistance” (AR) is associated with increased risk of vascular events. We aimed to compare different platelet function tests used in identifying AR and assess their implications on clinical outcome. We performed platelet aggregation studies on non-cardioembolic ischaemic stroke patients taking aspirin 100 mg/day and 30 non-stroke controls. Data were collected on demographics, vascular risk factors, and concomitant medications. Cut-offs for AR were (1) light transmission aggregometry (LTA) of ≥20% using arachidonic acid (AA), ≥70% using ADP, or ≥60% using collagen; and (2) VerifyNow® assay ≥ 550 ARU. Telephone follow-ups were conducted by study staff blinded to AR status to ascertain the occurrence of vascular outcomes (stroke, myocardial infarction, amputation, death). A total of 113 patients were recruited, mean age 65 ± 8 years, 47% women, 45 ± 15 days from index stroke. 50 (44.3%, 95% CI 34.9–53.9) had AR on at least 1 test. Frequency of AR varied from 0% to 39% depending on method used and first vs. recurrent stroke. There were strong correlations between LTA AA, VerifyNow® and Multiplate® ASPItest (r = 0.7457–0.8893), but fair to poor correlation between LTA collagen and Multiplate® COLtest (r = 0.5887) and between LTA ADP and Multiplate® ADPtest (r = 0.0899). Of 103 patients with a mean follow up of 801 ± 249 days, 10 (9.7%) had vascular outcomes, of which six had AR by LTA-ADP. AR by LTA-ADP is associated with increased risk of vascular outcome (p = 0.034). Identification of AR is not consistent across different platelet function tests. LTA of ≥70% using 10 µM ADP in post-stroke patients taking aspirin is associated with increased risk of vascular outcome.

Treatment of blunt cerebrovascular injuries: Anticoagulants or antiplatelet agents?

BACKGROUND

Blunt cerebrovascular injury (BCVI) is associated with cerebrovascular accidents (CVA). Early therapy with antiplatelet agents or anticoagulants is recommended. There are limited data comparing the effectiveness of these treatments. The aim of our study was to compare outcomes between BCVI patients who received anticoagulants versus those who received antiplatelet agents.

METHODS

We performed an (2011-2015) analysis of the Nationwide Readmission Database and included all adult trauma patients 18 years or older who had an isolated BCVI (other body regions Abbreviated Injury Scale [AIS] < 3). Head injury patients or those who developed a CVA during the index admission were excluded. Patients were stratified into anticoagulants and antiplatelet agents. Propensity score matching was performed (1:1 ratio) to control for demographics, comorbidities, BCVI grade, distribution, and severity of injuries. Outcomes were readmission with CVA and mortality within 6 months.

RESULTS

A total of 725 BCVI patients were identified. A matched cohort of 370 patients (antiplatelet agents, 185; anticoagulants, 185) was obtained. Mean age was 50 ± 15 years, neck AIS was 3 (3,4), and Injury Severity Score was 12 (9-17). The majority of the patients (69%) had high-grade BCVI (AIS ≥ 3). Overall, 3.7% were readmitted with CVA and 3% died within 6 months. Patients who received anticoagulants had a lower rate of readmission with CVA (1.8% vs. 5.72%; p = 0.03), and a lower rate of 6-month mortality (1.3% vs. 4.9%; p = 0.03). There was no significant difference between the two groups reading the median time to stroke (9 days vs. 6 days; p = 0.12).

CONCLUSION

The BCVI patients on CVA prophylaxis for BCVI have a 3.7% rate of stroke after discharge. Compared with antiplatelet agents, anticoagulants are associated with lower rates of CVA in the first 6-month postdischarge. Further studies are required to identify the optimal agent to prevent CVA in this high-risk subset of trauma patients.

LEVEL OF EVIDENCE

Therapeutic, level IV.

Clinical Significance of Acute and Serial Platelet Function Testing in Acute Ischemic Stroke

Background

We sought to investigate the clinical implications of platelet reactivity to aspirin and the variability in the platelet reactivity to aspirin during acute periods for the risk of vascular events in patients with acute ischemic stroke.

Methods and Results

This was a single‐center, prospective, observational study. The aspirin reaction unit was blindly measured at the following two times: after 3 hours of aspirin loading and on the fifth day of aspirin administration. High on‐aspirin platelet reactivity (HAPR) was defined as an aspirin reaction unit ≥550 IU. The primary outcome measure was the 1‐year composite of stroke, myocardial infarction, and vascular death. A total of 805 patients (aged 66±12 years, 61% male) were analyzed in this study. Ninety‐nine of 805 (12.3%) patients and 78 of 558 (14.0%) patients had HAPR at the time of the fifth day of aspirin administration and after 3 hours of aspirin loading measurements, respectively. Patients with HAPR than normal on‐aspirin platelet reactivity at the fifth day of aspirin administration measurement were more likely to have experienced 1‐year vascular event. HAPR at the fifth day of aspirin administration measurement was independently associated with a greater risk of experiencing 1‐year vascular event (hazard ratio, 1.84; 95% confidence interval, 1.07–3.19). Moreover, persistently HAPR substantially increased the risk of 1‐year vascular events (hazard ratio, 3.11; 95% confidence interval, 1.23–7.86).

Conclusions

These results suggest that HAPR during the acute stage of ischemic stroke increases the risk of subsequent vascular events and that serial aspirin reaction unit measurements may identify patients with acute ischemic stroke who are at a higher risk for vascular events. Additional studies are warranted to determine the appropriate treatments for patients with acute ischemic stroke with HAPR.

PFA-100-measured aspirin resistance is the predominant risk factor for hospitalized cardiovascular events in aspirin-treated patients: A 5-year cohort study

WHAT IS KNOWN AND OBJECTIVE

Aspirin therapy is the clinical gold standard for the prevention of cardiovascular events. However, cardiovascular events still develop in some patients undergoing aspirin therapy. Many laboratory methods exist for measuring aspirin resistance. Using the platelet Function Analyzer (PFA)-100 system, we aimed to determine the effect of aspirin resistance on hospitalized cardiovascular events (hCVE) in a 5-year follow-up cohort. We also sought to determine the impact of aspirin resistance on the relationship between common cardiovascular risk factors and cardiovascular hospitalization.

METHOD

Aspirin resistance was evaluated in aspirin-treated patients from the outpatient department. A total of 465 patients during a 5-year follow-up period were included in this study. The primary endpoint of the study was hospitalization for any acute cardiovascular event. The prevalence and associated risk factors of acute cardiovascular events were evaluated.

RESULTS AND DISCUSSION

Aspirin resistance was prevalent in 91 (20.0%) of 465 patients. Prior hospitalization history of cardiovascular events was highly associated with aspirin resistance (P = .001). At the 5-year follow-up, cardiovascular events were found to have developed in 11 patients (8 stroke and 3 myocardial infarction) who exhibited aspirin resistance (12.1%) and in 9 (4 stroke and 5 myocardial infarction) patients who did not exhibit aspirin resistance (2.4%) (P < .001). At the 5-year follow-up, multivariate logistic regression analysis results showed a strong association between aspirin resistance and cardiovascular events (adjusted odds ratio 4.28; 95% CI: 1.64-11.20; P = .03).

WHAT IS NEW AND CONCLUSION

PFA-100 measurements of aspirin resistance correlate with hCVE, as evidenced by both the past medical history and the 5-year follow-up. The logistic regression analysis results showed that aspirin resistance plays a larger role in hospitalized cardiovascular disease than do other cardiovascular risk factors.

Predictors of high on-aspirin platelet reactivity in elderly patients with coronary artery disease

Objectives

Previous studies have illustrated the link between high on-aspirin platelet reactivity (HAPR) with increasing thrombotic risks. The aim of our study was to investigate relative risk factors of HAPR in elderly patients with coronary artery disease.

Methods

Elderly, hospitalized coronary artery disease patients on regular aspirin treatment were enrolled from January 2014 to September 2016. Medical records of each patient were collected, including demographic information, cardiovascular risk factors, concomitant drugs and routine biological parameters. Arachidonic acid (AA, 0.5 mg/mL) and adenosine diphosphate (ADP, 5 µmol/L) induced platelet aggregation were measured via light transmission assay (LTA) to evaluate antiplatelet responses, referred as LTA–AA and LTA–ADP.

Results

A total of 275 elderly patients were included, with mean age of 77.2±8.1 years, and males accounted for 81.8%. HAPR was defined as LTA–AA in the upper quartile of the enrolled population. HAPR patients tended to have lower renal function (P=0.052). Higher serum uric acid (SUA) level, as well as lower platelet count, hemoglobin and hematocrit were observed in HAPR patients, with a higher proportion of diuretics use (P<0.05). Multivariate analysis revealed that SUA (OR: 1.004, 95% CI: 1.000–1.007, P=0.048), platelet count (OR: 0.994, 95% CI: 0.989–1.000, P=0.045), hematocrit (OR: 0.921, 95% CI: 0.864–0.981, P=0.011) and concomitant P2Y12 receptor inhibitors use (OR: 1.965, 95% CI: 1.075–3.592, P=0.028) were correlated with HAPR. Spearman’s correlation analysis demonstrated an inverse association of LTA–AA with hematocrit (r=−0.234, P<0.001), hemoglobin (r=−0.209, P<0.001) and estimated glomerular filtration rate (r=−0.132, P=0.031).

Conclusion

SUA, platelet count, hematocrit and P2Y12 receptor inhibitors use were independently correlated with HAPR. These parameters might provide novel therapeutic targets for optimizing antiplatelet therapy.

Validation of aspirin response-related transcripts in patients with coronary artery disease and preliminary investigation on CMTM5 function

Aspirin is widely used in the prevention of cardiovascular diseases, but the antiplatelet responses vary from one patient to another. To validate aspirin response related transcripts and illustrate their roles in predicting cardiovascular events, we have quantified the relative expression of 14 transcripts previously identified as related to high on-aspirin platelet reactivity (HAPR) in 223 patients with coronary artery disease (CAD) on regular aspirin treatment. All patients were followed up regularly for cardiovascular events (CVE). The mean age of our enrolled population was 75.80±8.57years. HAPR patients showed no significant differences in terms of co-morbidities and combined drugs. Besides, the relative expression of HLA-DQA1 was significantly lower in low on-aspirin platelet reactivity (LAPR) patients, when compared with HAPR and high normal (HN) group (p=0.028). What's more, the number of arteries involved, HAPR status and the relative expression of CLU, CMTM5 and SPARC were independent risk factors for CVE during follow up (p<0.05). In addition, overexpression of CMTM5 attenuated endothelial cells (ECs) migration and proliferation, with significantly decreased phosphorylated-Akt levels, while its inhibition promoted these processes in vitro (p<0.05).Our study provides evidence that circulating transcripts might be potential biomarkers in predicting cardiovascular events. CMTM5 might exert anti-atherosclerotic effects via suppressing migration and proliferation in the vessel wall. Nevertheless, larger-scale and long-term studies are still needed.

Determinants of reduced antiplatelet effect of aspirin in patients with stable coronary artery disease

Background

Aspirin is a cornerstone in management of coronary artery disease (CAD). However, considerable variability in the antiplatelet effect of aspirin has been reported.

Aim

To investigate independent determinants of reduced antiplatelet effect of aspirin in stable CAD patients.

Methods

We performed a cross-sectional study including 900 stable, high-risk CAD patients. Among these, 795 (88%) had prior myocardial infarction, 250 (28%) had type 2 diabetes, and 170 (19%) had both. All patients received 75 mg aspirin daily as mono antiplatelet therapy. The antiplatelet effect of aspirin was assessed by measurement of platelet aggregation employing 1) multiple electrode aggregometry (MEA, Multiplate Analyzer) in whole blood anticoagulated with citrate or hirudin using arachidonic acid (AA) or collagen as agonists, and 2) VerifyNow Aspirin Assay. Compliance was assessed by measurement of serum thromboxane B₂.

Results

Platelet count, prior myocardial infarction, type 2 diabetes and body mass index were independent determinants of increased AA-induced MEA platelet aggregation in citrate and hirudin anticoagulated blood (p-values ≤ 0.045). Similar results were found with VerifyNow. Prior coronary artery bypass grafting, age, smoking (MEA, AA/citrate) and female gender (MEA, AA/hirudin) were also independent determinants of increased platelet aggregation (p-values ≤ 0.038). Compliance was confirmed by low serum thromboxane B₂ levels in all patients (median [25%;75%]: 0.97 [0.52;1.97], range 0.02-26.44 ng/ml).

Conclusion

Platelet count, prior myocardial infarction, type 2 diabetes and body mass index were independent determinants of increased platelet aggregation, indicating that these characteristics may be key factors in reduced antiplatelet effect of aspirin in stable CAD patients.

Calprotectin and platelet aggregation in patients with stable coronary artery disease

BACKGROUND

Recent studies suggest that the inflammation-associated protein calprotectin may be implicated in the pathogenesis of coronary artery disease (CAD). However, the impact of calprotectin levels on platelet aggregation in CAD patients has never been investigated.

OBJECTIVES

We investigated the association between calprotectin levels and platelet aggregation in stable, high-risk CAD patients receiving aspirin as mono antiplatelet therapy. Furthermore, we aimed to investigate independent clinical and laboratory determinants of calprotectin levels.

METHODS

We performed a cross-sectional study including 581 stable, high-risk CAD patients. All patients received 75 mg aspirin daily as mono antiplatelet therapy. Platelet aggregation was assessed by 1) impedance aggregometry (Multiplate Analyzer) using arachidonic acid (AA) and collagen as agonists and by 2) the VerifyNow Aspirin Assay. Low-grade inflammation was evaluated by calprotectin, high-sensitive C-reactive-protein (hs-CRP) and interleukin-6. Platelet activation was assessed by soluble P-selectin, and cyclooxygenase-1 inhibition was evaluated by serum thromboxane B2, both measured by ELISA.

RESULTS

Calprotectin levels correlated positively with platelet aggregation according to Multiplate Analyzer (r=0.12, p=0.01). Additionally, calprotectin was positively associated with leukocytes (r=0.33, p<0.0001), hs-CRP (r=0.31, p<0.0001), interleukin-6 (r=0.28, p<0.0001), soluble P-selectin (r=0.10, p=0.02) and serum thromboxane B2 (r=0.10, p=0.02). Type 2 diabetes mellitus was an independent predictor of increased calprotectin levels (p=0.004), and trends were seen for body mass index (p=0.06) and smoking (p=0.07). Compliance with aspirin was confirmed by low serum thromboxane B2 levels in all patients (median [25%;75%]: 1.07 [0.52;1.87] ng/mL).

CONCLUSION

Calprotectin levels correlated positively, though weakly, with platelet aggregation and activation as well as serum thromboxane B2 in high-risk, stable CAD patients treated with aspirin.

No Additional Prognostic Value of Genetic Information in the Prediction of Vascular Events after Cerebral Ischemia of Arterial Origin: The PROMISe Study

Background

Patients who have suffered from cerebral ischemia have a high risk of recurrent vascular events. Predictive models based on classical risk factors typically have limited prognostic value. Given that cerebral ischemia has a heritable component, genetic information might improve performance of these risk models. Our aim was to develop and compare two models: one containing traditional vascular risk factors, the other also including genetic information.

Methods and Results

We studied 1020 patients with cerebral ischemia and genotyped them with the Illumina Immunochip. Median follow-up time was 6.5 years; the annual incidence of new ischemic events (primary outcome, n=198) was 3.0%. The prognostic model based on classical vascular risk factors had an area under the receiver operating characteristics curve (AUC-ROC) of 0.65 (95% confidence interval 0.61-0.69). When we added a genetic risk score based on prioritized SNPs from a genome-wide association study of ischemic stroke (using summary statistics from the METASTROKE study which included 12389 cases and 62004 controls), the AUC-ROC remained the same. Similar results were found for the secondary outcome ischemic stroke.

Conclusions

We found no additional value of genetic information in a prognostic model for the risk of ischemic events in patients with cerebral ischemia of arterial origin. This is consistent with a complex, polygenic architecture, where many genes of weak effect likely act in concert to influence the heritable risk of an individual to develop (recurrent) vascular events. At present, genetic information cannot help clinicians to distinguish patients at high risk for recurrent vascular events.

Prevalence of aspirin resistance in Asian-Indian patients with stable coronary artery disease

OBJECTIVE

To evaluate the prevalence of pharmacological resistance to aspirin therapy by measuring platelet functions using the technique of light transmission aggregometry.

BACKGROUND

Aspirin is the cornerstone of antiplatelet therapy in patients with coronary artery disease (CAD). However, a substantial proportion of patients manifest breakthrough thrombotic events despite regular intake of aspirin suggesting therapeutic resistance to aspirin.

METHODS

We prospectively studied 126 patients with stable coronary artery disease at a tertiary center, who were recruited after ensuring compliance with a single formulation of aspirin (enteric coated aspirin 150 mg). Platelet aggregation was measured using light transmission aggregometry with ADP (10 µM) and Arachidonic acid (0.5 mg/mL). Pharmacological aspirin resistance was defined as the combined demonstration of mean platelet aggregation of ≥70% with 10 µM ADP and a mean aggregation of ≥20% with 0.5 mg/mL A.A. Patients satisfying either one of the above criteria were defined as semi-responders. Patients satisfying neither criterion were defined as "aspirin responders".

RESULTS

Out of 126 patients with stable CAD, 64 % were responders, 36% were non responders (semi-responders = 34% and resistant = 2%). Of the laboratory parameters, only the total leukocyte count was significantly associated with the presence of aspirin resistance (P < 0.03).

CONCLUSION

Pharmacological resistance to aspirin is noted in 36% (semi-responders = 34% and resistant = 2%) of Asian Indian patients with stable CAD. Long-term follow up of these patients will assist in determining the clinical importance of this phenomenon. © 2014 Wiley Periodicals, Inc.

The clinical utility of Multiplate analyser measurement in platelet function testing following stroke and transient ischaemic attack

BACKGROUND

Platelet responsiveness to aspirin in people with cerebrovascular disease is poorly understood.

OBJECTIVES

To determine: (i) normal reference range, imprecision and reproducibility of the Multiplate instrument in healthy volunteers naive to aspirin; (ii) imprecision and reproducibility of the Multiplate instrument in acute stroke and transient ischaemic attack (TIA); (iii) the relationship between aspirin responsiveness and clinical outcome.

MATERIALS AND METHODS

We evaluated platelet function response to three agonists [Adenosine Diphosphate (ADP), Arachidonic Acid (AA), Collagen (Col)] using the Mulitplate platelet function analyser in a two-phase pilot study. In phase 1, we recruited healthy volunteers to determine the normal reference range and imprecision of the Multiplate instrument. In phase 2, we assessed platelet function in acute stroke or TIA patients presenting to hospital. These patients were bled within 24 h of presentation and between 12 and 24 h after ≥75 mg dose of Aspirin. Patients were followed up to 1 yr to assess mortality and recurrent cardiovascular event.

RESULTS

Overall, 29 healthy volunteers and 81 stroke/TIA patients were recruited. On assessing components of variance, Multiplate testing is reproducible and precise in volunteers and stroke/TIA patients. In stroke patients receiving aspirin, Bland-Altman plots show initial day 1 measurement provided a reliable measure of continuing response to aspirin at day 3. We defined one-third of patients as aspirin resistant [31.8% (95% CI: 22.1%-42.8%)] using cut off mean aggregation of ≥23.08% for AA and mean aggregation of ≥80.76% for ADP.

CONCLUSION

The Multiplate device gives reproducible, precise results in volunteers and stroke/TIA patients.

Chinese herbal medicine for aspirin resistance: a systematic review of randomized controlled trials

Aspirin resistance (AR) is a prevalent phenomenon and leads to significant clinical consequences, but the current evidence for effective interventional strategy is insufficient. The objective of this systematic review is thus to assess the efficacy and safety of Chinese herbal medicine (CHM) for AR. A systematical literature search was conducted in 6 databases until December 2012 to identify randomized controlled trials (RCTs) of CHM for AR. As a result, sixteen RCTs with a total of 1011 subjects were identified, suggesting that the interests of the medical profession and the public in the use of CHM for AR have grown considerably in the recent years. Tongxinluo capsule and Danshen-based prescriptions were the most frequently used herbal prescriptions, while danshen root, milkvetch root, Leech, and Rosewood were the most frequently used single herbs. Despite the apparent reported positive findings, it is premature to determine the efficacy and safety of CHM for the treatment of AR due to poor methodological quality and insufficient safety data. However, CHMs appeared to be well tolerated in all included studies. Thus, CHM as a promising candidate is worthy of improvement and development for further clinical AR trials. Large sample-size and well-designed rigorous RCTs are needed.

A Systems Biology Approach to Characterize Biomarkers for Blood Stasis Syndrome of Unstable Angina Patients by Integrating MicroRNA and Messenger RNA Expression Profiling

Blood stasis syndrome (BSS) has been considered to be the major type of syndromes in unstable angina (UA) patients. The aim of this study was to find the systems biology-based microRNA (miRNA) and mRNA expression biomarkers for BSS of UA. We identified 1081 mRNAs and 25 miRNAs differentially expressed between BSS of UA patients and healthy controls by microarrays. We used DAVID, miRTrail, and the protein-protein interactions method to explore the related pathways and networks of differentially expressed miRNAs and mRNAs. By combining the results of pathways and networks, we found that the upregulation of miR-146b-5p may induce the downregulation of CALR to attenuate inflammation and the upregulation of miR-199a-5p may induce the downregulation of TP53 to inhibit apoptosis in BSS of UA patients. The expression patterns of miR-146b-5p, miR-199a-5p, CALR, and TP53 were confirmed by qRT-PCR in an independent validation cohort including BBS of UA patients, non-BBS of UA patients, and healthy controls. miR-146b-5p, miR-199a-5p, CALR, and TP53 could be significant biomarkers of BSS of UA patients. The systems biology-based miRNA and mRNA expression biomarkers for the BSS of UA may be helpful for the further stratification of UA patients when deciding on interventions or clinical trials.